There are ongoing projects to devise approaches to monitor for prolonged periods of time, and ideally, even permanently, tag data, physical, chemical and/or geometrical parameter changes that may occur at any spot location over large structures.
Patent application no. VA2010A000018, assigned to the current assignee of the present invention and filed on Feb. 26, 2010, describes a multi-cell flexible sheet of organic polymer construction and having a finite or a theoretically unlimited length. The multi-cell flexible sheet includes a monolithically fabricated array of one or more types of cells having the same or different functionalities (e.g., sensor cells, active pixel cells of a large size display). The cells are juxtaposed to form a multi-cell sheet eventually supported on a flexible film. Such a bi-dimensional “tablecloth” array of self-consistent integrated circuit cells could be cut into pieces to be tailored for the need of the specific application without impairing the operability of all the cells spared by the cutting. This will eventually serve as a magazine of individually severable cells having an autonomous operability.
However, self-consistency of each individual cell follows the conventional approach of a pixel type organization, and is burdensome specially for sensing events that may occur at any location over a relatively large surface of a structure or body to be monitored. Communications with the external board by OLED devices and the embedding of a photovoltaic generator, battery or other energy storing device in each individual cell may be burdensome.
Another application assigned to the current assignee of the present invention, US2009/0033467 discloses a RFID device based on RF energy transfer and/or transmit/receive functions by near-field (magnetic) coupling that may be implemented through a hybrid transformer. A tag device (a sensor eventually coupled to it in a monolithically integrated circuit manner) has a primary inductor that is part of a RF near-field coupling structure for a reader device, and a secondary inductor that is either monolithically integrated on the tag/sensor integrated circuit (IC) or formed on a surface of the IC chip by post-processing (On-Chip-Antenna or OCA).
Near-field coupling of a reader with every tag device of a tablecloth array having a very large number of sensing nodes over a relatively large surface is labor intensive. This may require the reader to sequentially reach and pause momentarily over each node to be monitored, at a relatively short distance from it, to establish the necessary near-field RF magnetic coupling conditions.